Wind generator

ABSTRACT

The present invention relates to a wind generator. The wind generator comprises a body installed freely rotatably at a tower, blades installed at a leading end of the body, a gearbox for receiving rotational forces from the blades, and a generator connected to the gearbox for generating electricity. The blades are coupled with a blade angle adjustment unit so that the angles of the blades can be adjusted at predetermined angles according to the directions and velocities of winds. The gearbox comprises a planet gear coupled with a rotational shaft of the blades, a ring gear which has teeth formed on a radially inner surface thereof and engages with the planet gears, and a sun gear which engages with the planet gear and is connected with the generator. Teeth are formed on a radially outer surface of the ring gear so that teeth of a stop gear can be engaged therewith. The wind generator further comprises an electronic brake for controlling the stop gear in such a manner that it stops the rotation of the stop gear and thus causes the ring gear to become stationary.

TECHNICAL FIELD

The present invention relates to a wind generator using the inertiaforce of propeller-type blades, and more particularly, to a windgenerator in which blades thereof are configured to be rotated even witha general gentle wind so as to increase the rotational inertia force, adirection of the blades is always caused to conform to variable winddirections by means of free rotation of a body of the wind generator soas to increase rotational force, and angles of the blades are adjustedto reduce impact thereon and rotational speed of the blades, and aposition of the body is simultaneously changed in a desired direction toprevent damage thereto if a strong wind blows, thereby allowing highefficiency generation of electricity to be always obtained in a stablestate.

BACKGROUND ART

Recently, there have been a large number of developments of generatorsusing nuclear power, waterpower, thermal power, tidal power, wind power,solar heat and the like, which are inexhaustible or clean energysources, in view of exhaustion of underground resources and protectionof the natural ecosystem all over the world. There are problems in thatinstallation costs of conventional generators using undergroundresources as fuels are high, maintenance costs are continuously producedaccording to the use of the fuels, and wastes are produced due to theuse of the nuclear or thermal power, thereby resulting in environmentalpollution.

Therefore, there has been a need for use of a wind generator that cansolve the problems of conventional propeller-type generators and iseconomical in view of its installation area and in which installationcosts thereof is low and no pollutants are produced. A conventional windgenerator generally comprises a body installed freely rotatably at anupper portion of a tower, propeller-type blades installed at a leadingend of the body, a gearbox composed of a ring gear, planet gears and asun gear for increasing rotational force of the blades, and a generatorfor generating electrical energy using rotational force from thegearbox.

The wind generator using the propeller constructed as such is disclosedin U.S. Pat. No. 4,291,233 and Korean Patent No. 57585.

First, the principle of the general wind generator will be discussed. Arotational speed of the blades of the wind generator is determined toobtain an ideal maximum linear velocity of the blades, which is 80 to 90m/s, in the atmosphere having pressure of 1 atm. Then, the capacity androtational speed of the generator are determined, and a gear ratio ofthe gearbox (ring gear, planet gears and sun gears) is determined. Forexample, when it is assumed that a rotational speed of a 600 kWgenerator is 1200 rpm, an outer diameter of the blades is 46 m and arotational speed of the blades is 35 rpm, the gear ratio i of thegearbox becomes 34.3 (=1,200/35). Although a minimum wind velocity forstarting the blades under such conditions is 3 m/s, the blades can bestarted when power required for rotation of the blades is larger thanthe load factor, which is resistance of the gearbox, in a state wherethe gears of the gearbox are engaged with one another.

However, in the conventional wind generators, huge costs and asubstantial level of technical know-how are required for designing andmanufacturing the wind generators to minimize power loss when therotational force of the propeller-type blades rotated by wind energy istransmitted to the generator through the gearbox. The most importantfactor is the gearbox. Since a large resistance is exerted by the loadof the weight of the blades and by the respective gears engaged with oneanother in the gearbox in a state where the rotational force(efficiency) of the gearbox is lowered or the rotation of the blades isstopped due to very gentle winds, the blades cannot be started eventhough a gentle wind having a minimum wind velocity required for thestarting of the blades blows. Thus, the expensive wind generator becomesuseless.

Furthermore, since the conventional wind generators are constructed suchthat the body having the blades rotates about the tower so as to allowthe positions of the blades to freely change depending on winddirection, the blades are prevented from stopping due to a change inwind direction so that the force for generating electricity can beobtained. However, there is a problem in that if the wind directionsuddenly changes such as by a gust, the rotation of the blades may stopand the blades may also be severely jolted and then broken.

DISCLOSURE OF INVENTION

Accordingly, the present invention is contemplated to solve the aboveproblems in the conventional wind generators. An object of the presentinvention is to provide a wind generator, wherein a ring gear of agearbox is controlled to be stopped or rotated so that blades easilyrotate even with a gentle wind, and the desired rotational inertia forceobtained from the rotation of the blades is caused to be transmitted tothe gearbox so that a generator of the wind generator can be rotated,thereby obtaining the maximum operating time thereof.

Another object of the present invention is to provide a wind generator,wherein a vertical tail wing and auxiliary blades are provided at atrailing end of the body so that the blades are always positioned toconform to the wind direction, thereby improving the-efficiency ofelectricity generation.

A further object of the present invention is to provide a windgenerator, wherein a body rotation unit having an electronic brake isprovided to allow a body of the wind generator to rotate freely or stopby means of its own speed reducer motor, so that if a gust blows, thebody rotates in the wind direction and then stops to prevent the bladesfrom being broken, whereas the body freely rotates to cause the bladesto conform to the wind direction in normal operating conditions (otherthan sudden gusts) in order to improve the efficiency of electricitygeneration.

A still further object of the present invention is to provide a windgenerator, wherein the angles of the blades are adjusted depending onchanges in wind direction and velocity so as to maintain a predeterminedrotational speed and to stably operate a generator, and particularly,the blades are safely protected against strong winds or gusts so as toensure a prolonged life.

According to the present invention for achieving the aforementionedobjects, there is provided a wind generator including a body installedfreely rotatably at an upper portion of a tower, blades installed at aleading end of the body, a gearbox for receiving rotational force fromthe blades and increasing a rotational speed, and a generator connectedto the gearbox for generating electricity by means of the increasedrotational force received from the gearbox. The blades are coupled witha blade angle adjustment unit so that angles of the blades can beadjusted according to wind direction and velocity. The gearbox includesplanet gears coupled with a rotational shaft of the blades, a ring gearwhich has teeth formed on a radially inner surface thereof and engageswith the planet gears, and a sun gear which engages with the planetgears and is connected with the generator. A stop gear is installed tobe rotated while being engaged with teeth formed on a radially outersurface of the ring gear. The wind generator further includes anelectronic brake connected to the stop gear for fixing or rotating thering gear by intermittently controlling the rotational motion of thestop gear.

Further, in the wind generator according to the present invention forachieving the objects, an additional gearbox may be installed toincrease the rotational force, a body rotation unit for intermittentlycontrolling the rotation of a stop gear rotated while being engaged withteeth formed on a radially inner surface of a tower rotation unit isinstalled, and a trailing end of the body is provided with a verticaltail wing and auxiliary blades for guiding the blades so that theposition of the blades automatically conform to the wind direction.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an exploded and partially cut-away perspective view showing awind generator according to the present invention.

FIG. 2 is an exploded perspective view showing a gearbox of the windgenerator according to the present invention.

FIG. 3 is a longitudinal sectional view of the assembled gearbox of FIG.2.

FIG. 4 is a sectional view taken along line A-A of FIG. 3, showing gearsin an engaged state.

FIG. 5 is an exploded perspective view showing a second gearbox of thewind generator according to the present invention.

FIG. 6 is a longitudinal sectional view of the assembled gearbox of FIG.5.

FIG. 7 is a sectional view taken along line B-B of FIG. 6, showing gearsin an engaged state.

FIG. 8 is a sectional view showing a blade angle adjustment unit of thewind generator according to the present invention.

FIG. 9 is a partially cut-away view taken along line C-C of FIG. 8.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, preferred embodiments of the present invention will bedescribed in detail with reference to the accompanying drawings.

FIGS. 1 and 2 are a partially cut-away. perspective view showing a windgenerator according to one embodiment of the present invention, and anexploded perspective view of a gearbox of the wind generator,respectively. Reference numeral 1 designates a generator, referencenumeral 2 designates a body, reference numeral 3 designatespropeller-type blades, reference numeral 4 designates the gearbox,reference numeral 5 designates a blade angle adjustment unit, referencenumeral 6 designates a vertical tail wing, reference numeral 7designates propeller-type auxiliary blades, and reference numeral 8designates a tower.

The body 2 is installed at an upper portion of the tower 8 so as to berotatable by 360 degrees according to wind direction. The propeller-typeblades 3 are installed at a leading end of the body 2. The interior ofthe body 2 is provided with the gearbox 4, which is connected to andreceives rotational force from a rotational shaft 31 of the blades 3,and the generator 1 which is connected to the gearbox 4 and generateselectricity.

Since resistance exerted on the blades 3 varies according to changes inwind direction and velocity, a rotational speed of the blades 3 variesaccordingly. Further, the generator 1 should be supplied with therotational force corresponding to a certain rotational speed from theblades 3 in order to generate electricity. However, if the winddirection is proper and the wind velocity is high, the blades 3 arerotated excessively and thus subjected to overload. To solve theproblem, the blade angle adjustment unit 5 for adjusting angles of theblades 3 is installed at the leading end of the body 2.

In the blade angle adjustment unit 5, as shown in FIGS. 8 and 9, leadingends of the blades 3 are supported by a casing 51 in such a manner thatthe respective blades 3 are fixed to the leading end of the body 2 andsimultaneously rotatably arranged at three positions spacedequiangularly apart from one another by 120 degrees. Bevel gears 52 arefixed to the leading ends of the blades 3. Moreover, a rotational speedreducer 54 having a bevel gear 53 engaged with the bevel gears 52 fixedto the blades 3 is fixed to the casing 51. The casing 51 is fixed to therotational shaft 31. The casing 51 may be formed to be separable inorder to facilitate maintenance and exchange of the leading ends of theblades 3 supported by general bearings as shown in the figures. Therotational speed reducer 54 causes the bevel gear 53 engaged with thebevel gears 52 to be rotated or stopped so that the bevel gears 52 fixedto the blades 3 are kept in a rotating or stationary state. The anglesof the blades 3 are adjusted by means of the rotation of the bevel gears52 and maintained in an adjusted state as the bevel gears 52 arestopped. Electrical signals from the rotational speed reducer 54 aretransmitted through general ring connection terminals (not shown)between the casing 51 and the body 2.

As shown in FIGS. 3 and 4, the gearbox 4 comprises planet gears 41coupled with an enlarged flange portion formed at a leading end of therotational shaft 31 of the blades 3, a ring gear 42 having teeth 421 ona radially inner surface thereof with which the planet gears 41 areengaged to be rotated, and a sun gear 43 which is engaged with theplanet gears 41, connected with the generator 1 and placed in the centerof the ring gear 42. The planet gears 41 are rotated in a state wherethey are interposed between the sun gear 43 and the ring gear 42 whenthe rotational shaft 31 is rotated by the rotation of the blades 3. Atthis time, if the ring gear 42 is in a stationary state, the sun gear 43is rotated so that a shaft 431 operates the generator 1. On thecontrary, if the ring gear 42 is released from the stationary state, thering gear 42 is rotated by means of the rotational force of the planetgears 41.

Teeth 422 are formed on a radially outer surface of the ring gear 42 inorder to rotate or stop the ring gear 42, and a stop gear 44 is arrangedto be engaged with the teeth 422 and thus rotated or stopped.

The stop gear 44 is engaged with the teeth 422 formed on the outersurface of the ring gear 42 and maintains in its stationary state tocause the ring gear 42 to be stopped only when proper wind power capableof rotating the blades 3 is exerted on the blades. Then, as the planetgears 41 are rotated; the sun gear 43 and the generator 1 are operated.Furthermore, when an initial operation is activated or a gentle windblows, a large rotational force should be exerted on the blades 3 tostart the blades 3. Thus, in order to reduce an initial load factor, thestop gear 44 is caused to be rotated so that the rotational force of theblades 3 is not transmitted to the sun gear 43 and the generator 1through the planet gears 41 and only the ring gear 42 is simultaneouslycaused to be rotated. Thus, the blades 3 can rotate freely.

The stop gear 44 for stopping or rotating the ring gear 42 is coupledwith an electronic brake 45. which is operated by means of on/offintermittence.

The operation control of the electronic brake 45 of the gearbox 4, theblade angle adjustment unit 5 and a body rotation unit 83 is performedby a general electronic control unit (not shown) through input andoutput of electrical signals.

Meanwhile, although the planet gears 41, the stop gear 44 and theelectronic brake 45 have been configured so that four componentsconstitutes a group to maintain balance, it is not limited thereto. Itis also possible to arrange them so that two or three componentsconstitute a group.

Preferably, as shown in FIG. 1, in order to provide a constantrotational inertia force to the generator 1 so as to obtain an optimumlevel of electric power, when the rotational force received from therotational shaft 31 of the gearbox 4 is caused to be transmitted to adriving shaft 11 of the generator 1 so that the generator 1 is driven, aflywheel 12 which is a weight, is added to one side or both sides of thedriving shaft 11. Accordingly, a somewhat irregular rotational motion ofthe blades 3 according to the amount of wind is converted into aconstant inertia motion. Thus, it is possible to generate high qualityelectric power.

Another embodiment of the present invention is to increase therotational force by adding a second gearbox 4′ between the gearbox 4 andthe generator 1, as shown in FIGS. 5 to 7. The second gearbox 4′comprises planet gears 41′ coupled with an enlarged flange portionformed at a leading end of a shaft 431 of the sun gear 43 of the gearbox4, a ring gear 42′ having teeth 421′ on a radially inner surface thereofwith which the planet gears 41′ are engaged to be rotated, and a sungear 43′ which is engaged with the planet gears 41′, has a shaft 431′connected with the generator 1 and is placed in the center of the ringgear 42′.

As described above, as a method of connecting the gearbox 4 and thesecond gearbox 4′ with the generator 1, the blades 3 and the planetgears 41 of the gearbox 4 are connected with each other by means of therotational shaft 31, and the sun gear 43 or 43′ of the gearbox 4 orsecond gearbox 4′ and the generator 1 are connected directly with eachother by means of the shaft 431 or 431′. Alternatively, for the purposeof convenience of assembly or maintenance, the rotational shaft 31 orthe shaft 431 or 431′ may be connected by a coupler 10 or 10′ in themiddle thereof, as shown in FIG. 1.

Further, as shown in FIG. 1, the coupling of the body 2 and the tower 8in the present invention is made in such a manner that teeth 81 areformed on a radially inner surface of a tower rotation unit so that thebody 2 freely rotates by 360 degrees in a state where the body 2 iscoupled with the tower 8, and the body rotation unit 83 forintermittently rotating a stop gear 82, which is engaged with the teeth81 and rotated, is fixed to the body 2. Since the body 2 is rotatedthrough reduction gears disposed within the body rotation unit 83itself, the position of the body 2 can be changed when it is likely thatthe blades 3 may be broken due to the occurrence of a gust or the like.

Furthermore, the vertical tail wing 6 for causing the position of theblades 3 to conform to the wind direction is installed in the center ofa trailing end of the body 2 of the wind generator according to thepresent invention. The propeller-type auxiliary blades 7 are installedin the vertical middle of a rear end of the tail wing 6, i.e. the middleposition where the wind passing by the blades 3 advantageously contactthe auxiliary blades. Thus, the body 2 is not jolted and is kept in astable position. Further, the auxiliary blades 7 are configured to berotated in a direction opposite to the rotation direction of the blades3 subjected to the wind power, so that jolting of the body 2 isprevented and the change in the position of the body can be smoothlymade according to the wind direction.

The operating principle of the wind generator according to the presentinvention will be described below.

As can be understood from FIGS. 1 and 3, if a wind blows, the windcauses the blades 3 to rotate and then passes to the trailing end of thebody 2. Thereafter, the wind passes by the vertical tail wing 6 and thencauses the auxiliary blades 7 to rotate.

In such a process, the rotational force of the blades 3 rotates theplanet gears 41 of the gearbox 4 through the rotational shaft 31, andthe planet gears 41 are rotated while being engaged with the teeth 421formed on the inner surface of the ring gear 42 so as to rotate the sungear 43. The rotation of the sun gear 43 provides an increasedrotational speed larger than that of the blades 3 and operates thegenerator 1 through the shaft 431 of the sun gear 43. Thus, electricityis generated.

In the meantime, after the blades are stopped as wind power exerted onthe rotating blades 3 gradually weakens, restarting the rotation of theblades 3 can be made only when a wind power larger than the total loadwhich is the sum of the weight load of the blades 3, the loads of therotational shaft 31 and the respective gears of the gearbox 4, and theloads exerted on the generator 1 is produced. Therefore, it is difficultto rotate the blades 3 with a gentle wind. Accordingly, in order torotate the blades 3 even with a gentle wind, the load factor resultingfrom the total load should be lowered. To this end, the stationary ringgear 42 should be rotated. When the ring gear 42 becomes rotatable, thering gear 42 is also rotated together when the planet gears 41, whichhave received the rotational force from the blades 3, are rotated. Atthis time, since the transmission of the rotational force to the sungear 43 and the generator 1 is blocked, the load factor is minimized toenable the blades 3 to be started. The blades 3, which have begunrotating with a gentle wind obtains a gradually increased inertia forceresulting from the rotational motion and thus a predetermined rotationalforce. At this time, the rotation of the ring gear 42 is stopped and theplanet gears 41 drive the generator 1 through the sun gear 43.

In particular, if the second gearbox 4′ is added as shown in FIGS. 5 and6, the rotational speed is further increased. Thus, it is possible toobtain an excellent effect in that the efficiency of electricitygeneration of the generator 1 is more improved. However, the load factorin the initial starting of the blades 3 engaged with the respectivegears of the second gearbox 4′ is increased, so that it is difficult toinitially start the blades 3 with a gentle wind. Accordingly, in orderto cause a minimum load factor to be applied to the generator 1, thering gear 42 is caused to be rotated and then to be stationary when anoptimum rotational force is obtained.

As a method of fixing or rotating the ring gear 42, as shown in FIGS. 3and 4, the stop gear 44 rotated while being engaged with the teeth 422formed on the outer surface of the ring gear 42 so as to be rotated iscoupled with the electronic brake 45 and thus rotated or stopped bymeans of the on/off intermittence of the electronic brake. Therefore,the ring gear 42 is operated to be stopped or rotated.

Further, in a state where the body 2 is coupled with the tower to freelyrotate as shown in FIG. 1, the stop gear 82 rotated while being engagedwith the teeth 81 formed on the inner surface of the rotation unit ofthe tower 8 is also rotated while being engaged with the teeth 81 sothat the body 2 freely yaws according to wind direction when optimumwind power is exerted thereon. Then, if a gust blows and thus the body 2and the blades 3 are subjected to an impact and jolted, the bodyrotation unit 83 stops the rotation of the stop gear 82 so as to stopthe movement of the body 2, thereby preventing the body 2 from beingbroken.

Moreover, the vertical tail wing 6 installed at the trailing end of thebody 2 guides the body 2 so that the position of the blades 3 conformsto the wind direction. That is, the wind is caused to collide directlywith wing surfaces of the blades 3 so that a smooth rotational force canbe obtained. Further, the auxiliary blades 7 are rotated in thedirection opposite to the rotation direction of the blades 3 to preventjolting of the body 2 and maintain the balance of the body 2 and serveto guide the body 2 to be rotated in the wind direction. In such a way,the auxiliary blades 7 improve the efficiency of electricity generation.

Furthermore, as can be understood from FIGS. 8 and 9, if the wind powerexerted on the blades 3 is weak or strong, the rotational speed reducer54 of the blade angle adjustment unit 5 is operated so that the bevelgear 53 rotates the bevel gears 52 to adjust the angles of the blades 3.Since the angles of the blades 3 are adjusted according to the rotationof the bevel gears 52, optimum angles of the blades 3 can be maintained.Particularly, in a case where a strong wind blows, in order to minimizecontact areas of the wing surfaces of the blades 3 with the wind, tiltangles of the blades 3 are adjusted to reduce the impact thereon due tothe wind and to simultaneously prevent over-rotation of the blades,thereby ensuring safe use thereof. In order to provide optimum operationconditions, it is also possible to fix the blades 3 after the angles ofthe blades 3 have been adjusted.

According to the wind generator of the present invention, the loadfactor applied to the blades is minimized so that the blades can beeasily rotated even with a gentle wind. Then, when a desired rotationalinertia force is exerted on the blades, the rotational force of theblades rotates the generator through the gearbox so as to obtain amaximum operating time. The efficiency of electricity generation can befurther improved by means of the additional gearbox. The vertical tailwing and the auxiliary blades installed at the trailing end of the bodycause the position of the blades to always conform to the wind directionso as to improve the efficiency of electricity generation. If a gustblows, the body, which is freely rotating, is stopped and the angles ofthe blades are adjusted to eliminate resistance to the blades so thatthe blades are prevented from being broken. The position of the body ofthe wind generator can be controlled in a desired direction.

1. A wind generator including a body installed freely rotatably at anupper portion of a tower, blades installed at a leading end of the body,a gearbox for receiving rotational force from the blades and increasinga rotational speed, and a generator connected to the gearbox forgenerating electricity by means of the increased rotational forcereceived from the gearbox, wherein: the blades are coupled with a bladeangle adjustment unit so that angles of the blades can be adjustedaccording to wind direction and velocity, the gearbox includes planetgears coupled with a rotational shaft of the blades, a ring gear whichhas teeth formed on a radially inner surface thereof and engages withthe planet gears, and a sun gear which engages with the planet gears andis connected with the generator, a stop gear is installed to be rotatedwhile being engaged with teeth formed on a radially outer surface of thering gear, and the wind generator further includes an electronic brakeconnected to the stop gear for fixing or rotating the ring gear byintermittently controlling the rotational motion of the stop gear. 2.The wind generator as claimed in claim 1, wherein the blade angleadjustment unit includes a casing which is fixed to the leading end ofthe body and of which a leading end is supported so that the respectiveblades can be rotated, bevel gears fixed to leading ends of the blades,and a rotational speed reducer which is fixed to the casing and has abevel gear engaged with the bevel gears of the blades.
 3. The windgenerator as claimed in claim 1, wherein a second gearbox includingplanet gears, a ring gear and a sun gear is additionally installedbetween the gearbox and the generator so as to increase the rotationalforce.
 4. The wind generator as claimed in claim 1, wherein teeth areformed on a radially inner surface of a tower rotation unit with whichthe body is coupled to freely rotate, and the wind generator furtherincludes a body rotation unit for intermittently controlling therotation of a stop gear rotated while being engaged with the teeth. 5.The wind generator as claimed in claim 1, wherein a trailing end of thebody is provided with a vertical tail wing and auxiliary blades forguiding the blades so that the position of the blades automaticallyconform to the wind direction.
 6. The wind generator as claimed in claim1, wherein a flywheel that is a weight is added to one side or bothsides of a driving shaft of the generator in order to provide a constantrotational inertia force to the generator.